Cartilage invasion patterns in laryngeal cancer.

The cartilaginous invasion determines the T and is one of the most common sources of mistake in tumor staging. Also it is of great importance when planning any therapeutic alternative. In the latest revision of the TNM classification a clear distinction is made between infiltration of cartilage without going through it, considered a T3 recently and that would be a T4 according to the previous classification, and those going through the cartilage, classified as T4a. While this classification makes the difference in depth of infiltration, it does not emphasize the extent of invasion. This paper provides a detailed description of the laryngeal cartilage tumor infiltration by whole organ serial section in which the invasion is considered both horizontal (transcartilaginous) and vertical (extent of invasion) and establishing patterns of three-dimensional infiltration of the cartilage. This is a cross-sectional study of prevalence. 275 records of patients treated for laryngeal squamous cell carcinoma between 1995 and 2000 were reviewed. The pathological processing of laryngectomy surgical specimens was performed following the method of whole organ serial section described by G. F. Tucker. The following patterns of cartilaginous infiltration were defined: (1) transcartilaginous infiltration; (2a) partial focal infiltration of the cartilage: infiltration not going through the cartilage but occupying one third or less of its extent; (2b) partial extensive infiltration of the cartilage: infiltration occupying two thirds or more of its length and (3) no cartilage infiltration: tumor in contact with the cartilage (paraglottic space) but without affecting it. 161 patients met the inclusion criteria. The most frequent tumor location was supraglottic (58 cases) followed by glottic (47). 109 patients (67.7 %) were treated with total laryngectomy. Partial surgical techniques were performed in the remaining cases. TNM tumor staging was performed according to the results of pathological study (pTNM). 72.06 % (116) were classified as advanced laryngeal tumors (pT3 and pT4). 46 % of patients showed some extent of laryngeal cartilage infiltration (thyroid, cricoid, arytenoids, epiglottis). The cartilage most frequently infiltrated was the thyroid in 48 patients (29.8 %) and when it is affected, in most cases (66.7 %), the infiltration is transcartilaginous. The next most common pattern is partial focal infiltration (27 %). In the cricoid cartilage, the most common pattern of infiltration is focal partial infiltration (52.6 %). Of the 19 cases with infiltration of the cricoid, there are 12 cases with extra laryngeal invasion through a cricothyroid membrane perforation. The study of laryngeal cancer by laryngeal whole serial section has been proved to be very useful in offering a high precision pTNM staging and a detailed description of the infiltration of cartilage. We have seen that when the thyroid cartilage is infiltrated the tumor often passes through the cartilage. However, there are cases where the tumor is extremely aggressive, being very widespread in cartilage thickness without actually crossing it. The isolated infiltration of the cricoid cartilage is exceptional.